colorectal cancer molecular diagnostics · 2014-01-29 · colorectal cancer molecular diagnostics...
TRANSCRIPT
Colorectal cancer
Molecular diagnostics
Rachel Butler
All Wales Genetics Lab
• Jass model (Histopathology, 2007)
• Current molecular markers
• Future molecular markers and analytical
tools
Molecular diagnostics
2. CIMP-high, partial
methylation of MLH1,
BRAF mutation,
chromosomally stable,
MSS or MSI-L, origin
in serrated polyps
(8%).
Pathways of Colorectal Carcinogenesis (Jass)
5. Lynch syndrome, MSI-H,
CIMP-negative, BRAF
mutation negative,
chromosomally stable, origin
in adenomas (3%).
3. CIMP-low, KRAS
mutation, MGMT
methylation,
chromosomal
instability, MSS or
MSI-L, origin in
adenomas or serrated
polyps (20%).
1. CIMP-high, MSI-H, methylation of
MLH1, BRAF mutation, chromosomally
stable, origin in serrated polyps, known
generally as sporadic MSI-H (12%).
4. Chromosomal
instability, MSS,
CIMP-negative,
origin in
adenomas (57%).
Epigenetic DNA Methylation
CpG Island Methylator Phenotype: CIMP
• coordinated methylation of genes:
MLH1, CDKN2A/p16, MGMT, IGF2, RUNX3, SOCS1, MINTs and others
• associated with BRAF mutation.
• 10 – 20% colon cancers.
2. CIMP-high, partial
methylation of MLH1,
BRAF mutation,
chromosomally stable,
MSS or MSI-L, origin
in serrated polyps
(8%).
Pathways of Colorectal Carcinogenesis (Jass)
5. Lynch syndrome, MSI-H,
CIMP-negative, BRAF
mutation negative,
chromosomally stable, origin
in adenomas (3%).
3. CIMP-low, KRAS
mutation, MGMT
methylation,
chromosomal
instability, MSS or
MSI-L, origin in
adenomas or serrated
polyps (20%).
1. CIMP-high, MSI-H, methylation of
MLH1, BRAF mutation, chromosomally
stable, origin in serrated polyps, known
generally as sporadic MSI-H (12%).
4. Chromosomal
instability, MSS,
CIMP-negative,
origin in
adenomas (57%).
Colorectal cancer pathways
Noffsinger AE. Ann. Rev Pathol. 2009;4:343-64.
Predictive and prognostic markers
• MSI – Lynch syndrome
– No benefit with chemo in sporadic tumours
• KRAS – don’t respond to EGFR MAb – p.G13D ??
• BRAF – poor prognosis
Microsatellite instability • Lynch syndrome
– MSI analysis or MMR IHC
– BRAF p.V600E or MLH1 methylation
– Determines diagnosis and management
Or
• Sporadic CRC – MSI analysis or MMR IHC
– BRAF p.V600E or MLH1 methylation and/or FH (i.e. Not Lynch!)
– Determines treatment
KRAS: -ve predictive marker
• Monoclonal antibody to EGFR (Cetuximab) only effective in patients whose tumours are KRAS wild-type
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10 12 14 16 18
Time from Randomisation (Months)
Pro
port
ion A
live
Cetuximab
BSC
Cetuximab
BSC
117 108 95 81 52 34 20 9 6 2113 92 69 36 24 17 12 5 3 3
Study arm MS
(months)
95% CI
Cetuximab +
BSC
9.5 7.7 –
10.3
BSC alone 4.8 4.2 –
5.5
Tejpar et al, JCO 2012
The EGFR
MAb story
The EGFR
MAb story
Response to EGFR
MAb also reduced by
tumours with
mutations in NRAS,
BRAF and PIK3CA,
and EREG low
expressors
FOCUS4
• Biomarker trial to identify and validate
treatments for:
– BRAF mutations
– PTEN loss and PIK3CA mutations
– KRAS and NRAS mutations
– EGFR pathway dependent (i.e. WT for
everything including MMR IHC)
• Determine EREG expression status
Parallel testing for multiple
mutations….
Many molecular tools available…….
Cost
Sensitivity and
specificity
Availability
of
equipment
How many
markers
required…now
and in the
future
Ability to
work on FFPE
Flexibility to
add to panel Availability of
commercial (CE-
marked) test
Mutation type
analysed
Batching
and RTs
Molecular tools
KRAS, NRAS, PIK3CA, (PIK3R1), BRAF
KRAS c.35G>A
(p.Gly12Asp)
My prediction…. We will test diagnostically for
• KRAS, NRAS, BRAF and PIK3CA
• MSI (or MMR IHC) in Lynch and sporadic tumours
• Possibly start to use gene expression markers
• Start using multi-gene testing platforms [cost vs required markers]
• All will require EQA
Many thanks
FOCUS4
UK NEQAS